SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f91598b89a9201dcd3d4a7db1e956496a5a20b75fa60ab8f639a3fc255a04418' 
  AND token = 'F6+hmpABj/FNJjEnG/xQFOH2jNJ2LdiPrjWghOnJPUo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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