SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36cd2fa9cd040b272f947675200d4dd8312a59007b2509394bca85f40f58458f' 
  AND token = 'T1dGWvR3mh6gbD+Zpg7ne1Zj3AqVYss9TztJUlMI78M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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