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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b4296b55cd888ece7c904d44e088a487da9e6036eeaf0a3ad5dfe1d92f513164' 
  AND token = '77j9Ep3bSDnS1dg8p7LQ4UJNyqfvmAA7Q8b7CE8BFCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}