SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de88307503a1db9363f3b4b55ff9808ee64f5d2862b148a71aa85fc67b186d11' 
  AND token = '1dp+b6p4eHMTLs7nn+c27yAEPFV9jGGw2h/F8zBmXWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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