SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ac4b64da822a1d80924c08109b78332f90274e65da4cbfac81456e638599d18' 
  AND token = 'owlxjXmVTC4DfUrS72o6vJNzkWf932QYZh85YyCJa5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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