SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21bac4d13a5cf30ffafddef4ddd1f2821247191221499584fc3b6e204ea78b24' 
  AND token = 'Zg0CR2NolGSTegDHITuqbBi/GX0Jtwxhq7SsSCRN0U8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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