SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bbf9dc88b34800312b2b1b2fd7f3a034933d9995b2f017e2974692b8cd38237' 
  AND token = 'H6xmh7U+YW7QMpmo13GqllduvyB8X7qP47wnEme65T0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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