SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f493fea1e802ab9299740240759d95112c32d26b41a07bbd104951e1086afc4e' 
  AND token = 'K3X4WlTV/wLHjFxUS3BLPwzAxy5KjGUXbFjRn+iW29k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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