SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbcfba5deb1c465468151fa943fbf5e9cfea5876e3c02051d45c911542828a1b' 
  AND token = 'iWcc544oOlTUxbLQE/5FiOzBScglFzDIYDwaLLiQBco=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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