SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7004f574def3c6500353a7b884708427a8e719d208c609fb31dda587767b4e55' 
  AND token = '5DoP/mdba7Ly2NI+lc8UmJ2VRkyxoLVepUnWJXykcZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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