SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9f5db25836e95a099eb66637204484e3ff21b1ccaa647c9a1d805d144e4dc4d' 
  AND token = 'QCvtzSKzleXPvhkV5AJYCaWIQ5VAy4wUdAuXgubHrMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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