SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68f1136d914b5d3d8d14071f4e8145dd6fa200e504368e2095dde1987433e4fe' 
  AND token = 'ul1ntM9S7gRdFrHyqrHH58U6cOqVDFOtSQirx8477V4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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