SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '278ff8b64114def2db7101fc7fe0e9230356320526dd01ed349881bd5451781a' 
  AND token = 'wckvGls4W8qnd1z14kFtK8v/XNRNxcj9w98wgg4sj9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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