SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d3d3796cf39d55b2306d43954da2354af1c3126ffbc9153864e974a193e5204' 
  AND token = 'WM+MqhjjmCnI3PHUdkhcZO7AhZpt/mtBRlKzaw2I+K0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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