SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf8cf179403f154132d91fd89f51e8fb2d0d4f3a3fdbf3de0f1eb24237d71f0f' 
  AND token = 'YWcFKNCnqxWvKHCAxFWreXCfuLKrSSD9PKxftbcpLaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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