SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51738af2627ff590926d31372dfaa86aa187f07d93d88534168321c8cb89cb80' 
  AND token = 'l2kjXLFFw7Yq0GM2/KMDO3yWqhpBj2PJoTJ64Ov5/rk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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