SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb0f21136d131130594c565b5ae31a550dd66156e717671ce166d2645064cbe0' 
  AND token = 'eOxKSc9ddQK2etfDUJZEwQu86fWNPf3WCR1/DHXMGxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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