SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1f1956bd901fb47cf4497f176092b956cae5da11354e18f4b84a45c15976814' 
  AND token = 'n++xaIBZXOBuVmJEezghyrTwOQhvJj3jVQgb7PSDeMo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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