SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d82c1d45b6f2cc1b128d9bd045659147185d68812b27adf1814a268215c1435' 
  AND token = '46nOB+885zmoF1n9sGN4XIoNba0LBpnLtRyjOKr03kA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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