SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37f79377cd0994c8414fe1e0fa942aa8b3feb4deeae93a07ecb346395b370d90' 
  AND token = 'uRhkmA0YK2uTvF/fHzb1ZJeMery1e7XlQHAUb4PBj/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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