SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c259bcd2515b398066331d9cddf41ae459099d6ae3695fd53213588961fd30e' 
  AND token = 'YUvl+UHqdB41/WCFnXfRC9ISzzhTBMFmHBm+sDOQBYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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