SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4982f027e813840df33b54ccc03696d53ff001b0508fa411e7a375642b886b4' 
  AND token = 'n+xxzjLLhJLdEMlvEuZMh5cdxo8CDS97IyrP4fQdRsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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