SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1f34337bc2911e868361f52702e6c40d8dcc2a5e808505fbb4fb375fef7afd8' 
  AND token = 'OkdrY3pcjm4AVFT7tsebXc1HcuRVGdtRz+3/C3bfxHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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