SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4d74f98867fe184601abb2352ddc29a3f2984e5223efdc2de253b56630a64da' 
  AND token = 'jlgEAOqOiWm6+kOBd1FbDMytDGkSekBsmJmccEzoTv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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