SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae27f2e2ca7c24e2dce4656dbd775a2ea58ca160e0c11a1b123fe8bfe2738736' 
  AND token = 'MYJ5qmYZYuJoGBg1b25ZWqyVpEUDmL3SB1kPDjXbKm0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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