SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '577d37d83adc9021f2e333dd2f9c8466e79981e755b46a1f9bd2b9edfa73163a' 
  AND token = 'sUjyKFbRpPGg5fDmeNALjsq4xrYSiUuf971gY1jzQOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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