SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e96e35d09ee097374e53d3f440e2f48281a4973d6d09667414e622c5eb4ea1c' 
  AND token = 'xXEpyNhzhU7aMJO/RH0ZM/qZcYwLGyVFUU/+QKP9xfk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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