SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6485df375994e65bccbfa259e5910c394b5effa5f19914daf844677a87ebb0d2' 
  AND token = '0YAnXs4/zugtUnbpAshTnWAvAcBugEOoWVfZxemmc8k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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