SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e03ea46b00399e872a27a58d4427cb9061ec52f99b5da15fbb053eaf972c3f48' 
  AND token = 'R2o+q593sJZVOsh1tmwNhkpwbRfUCzmZqK8qLBDfrmk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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