SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9988690d4da2d466f403220e277229df6a17064ad0dd3cad0802a1ac93ef77e' 
  AND token = 'WkXIveadZFgZsUHQ9sTKUsT05ccI2jEDvbFb/HMCrMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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