SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d21b172c8e5d5a446e2346e553ff4cebc08a949f3433cf5662bdf9294b2859f' 
  AND token = 'cPVjPdWmU/g0ZkbDiNmYUa1BK0izlGZFwGiU4xrxack=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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