SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a460738552b50e1e8f9257727bff381ee8cb9f88ecf187bca314430f9325126b' 
  AND token = 'pjE/DtrFziPtk7il+NhU62cIwrsVJHaOjvsjDMfdkhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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