SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88d828a9a611e40aa005c46e468bc0ffc24b085e701630b74e41224d2c70fca9' 
  AND token = '4UbucJLj3TaXEMDV5TuRtlzl2NBnSRVD+Glhh/o+C4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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