SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '038d2c1619850236b53f12a50e052f03308d5e16f3dfc891dd5c0757acd4b4e7' 
  AND token = 'yuPyxJZxb0fBEK+9gms6osYFEk1ioUF5yOwllGj6NmY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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