SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '506d887e7c95e3a7fe6466400272e322b5b358122f8c408da74750ba0046afb4' 
  AND token = 'KeKabCURq09UrhdxRMTDt+9LU46XvISTchX8SIkufgE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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