SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '857717720dff7a69bfcfeff7e747069802d30e8b53e87879877c97565f818960' 
  AND token = 'by3a0PhYsvWZ7ludDN5uf+53uqsOJOKGweXS6Wd+rdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}