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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97f5c98996f3b0bce1318a6ca0b802b9b5ea2f83b8c4d57c54d43fae52ce60dd' 
  AND token = 'djBg89POtNeGcpW1LtVCs1xcYFrqKOGFIFT4o+n3MRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}