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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5e3eb0c5c7ab7c27aaa0c2f54d04232d7f608fcc02dcaa51ab3dd9e479fd1c6' 
  AND token = '/4s3vTj2EBtuCRLd7FqDhKWQr6/Ht2u3cxmIq6CBxZk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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