SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db3abb87529505f8d675d980b78adf6163025861ba923cd84c65fcf090958fd2' 
  AND token = 'ElMcAB1aGqn+KE3p9DK54+uH9sISohSaVTB435kGVjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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