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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2f431a1a1fefdaa44895e99920319e7c41ea5e0db8812fd3ded4cf4b3211ccc' 
  AND token = 'IT1AdbdIYWuwpIbBFitBUY4GEAQUmnvYJ0jSawY/Nmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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