SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4975fd2692d0371bd5abf9f723874e8b7743cb3909900bd28c9eddf84432c38f' 
  AND token = 'VnLnNRy3VBGMQ4Hvv+2TgHU44KyyzLMfSk1qY86K1N4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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