SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac400edaa539a7878cb1e406d14b128b49c4460d95ef82c50c48a9189cd3f5e4' 
  AND token = 'MR5vgophMUGOUkWjMmJT3TdpYALvzyJo93RVZ/3GJCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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