SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d3e4362c8a2a61b655547c3ec2746b75697df9c1a8f07b524131ddaa3a73ff2' 
  AND token = '4qwSkBDy3J+nKoiJWE4lpe6hzzipGdQPVN6wjwdAhAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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