SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67b51f6e2d297f37ef7bc04e1e43b1010e52b6c755e6bf8bc3f054f13950d7c5' 
  AND token = '5Xi1popqeEQzN+GWYIwg+vnytri5vyVnj/SMhSqhJUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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