SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b29692bd421f6a63449ed97f7932ebde41812604c1c0441f38792c5e1af75599' 
  AND token = 'DsFHRhSkkkjbqrYRl7xMdiQTEaZoUP3yns7OR0ClI2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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