SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1af1743efb7c72228850ae99648a3c625961e9332868de9eabf662db3fc264b8' 
  AND token = 'A4qDHvkcLNa9k9ch+TP5euSks+EyLfjb5Bh2mQbdSzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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