SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18092a7baf5a4335a02ec173e1dad753941fb4f92834a949459a0bdc5a5f0807' 
  AND token = 'U+77eZUxCK0/rqIbix53mXIqnazskcWXc+akOw/hcU0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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