SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa751086876ab1ab5fd7b76a4f169e75f18185906b8b8db3f05c6ad52fd804a7' 
  AND token = 'QcJabZ8BCvqGhE+Lh/w3V7uNCDJhrAGudUFOGFMFNcg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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