SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b55031fdde58c6c0a3d008b1185ad6d7b9650fdd0230296d92aacce83d5ee56c' 
  AND token = 'i6C4IDU5R7VEqKLkz+KZ2rjUtFdR6KFVdoVwPt45EmI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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