SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c62352b3d67be5390b5f50aed0b354e40e7cd84eefe71100f916c44c6c35941f' 
  AND token = '2Yoj9/hj0CSdJ3paDwllUFfuP/tC+Uu7vzkH58msBtY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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