SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f825dadf3de3b12c1d86ae69416873886b398b29cd8053efda01a4533697656' 
  AND token = 'fWOQVC6hm3KBAIzIPgJyOwccFyGkgcQiPkc+Rw5zNLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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