SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fd8d9d38e6b042632cb31194025c84c49836fff6f3d53ba59e638b417e81213' 
  AND token = 'b+j4vVDzaBEgBIoDvT1R6PNQxEUYtTpznoi7xliLPMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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