SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1647137001055553c9022eb72671b4835452456c2a5ba2a3dc74f06d1985598' 
  AND token = 'uJ6KjGNSCggnd5GT8vWjBuijWDvi334X7qJKmVhl4X4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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