SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70d478eb976ffb39f46fd9f555b2ca61d41a2d6c83a821e5540abba351865bcb' 
  AND token = '4XL0TOI9CCsY0MnwVHBQCxlrY3iDkeWlU3NmsiiR27s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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