SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc6eeec099fd4aeb43c84b35cc261ab44ff9fe40323929ac86e736ed4283b5a4' 
  AND token = 'UdvKSha1SXE9kVBGZmLJXCoKIgNOUB1Agb1Nkoy6xL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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