SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd5c52019e22c997e02082cef76a903a3ea1b1e321d5a97dd404fb2f24265b8f' 
  AND token = 'V12butIuYl2zb2DLWT8FJljJ2/FFVejwuMWe26h4llc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}