SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e848cd38f5270642eb8e6ff171652605c9a8b8e8d1f5752fed03a8cc37486276' 
  AND token = '4aoICaY4s4qdnR8ZH5FSVTfEwrAVyh7UviidbUESi1Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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