SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75bd4970700d63b0543f0cc8a156a6ad0c3794c20f1264a2800eab061f5382da' 
  AND token = 'P30G6cvAbsmKZYO6+YNUpPs9ohNfmUZDb450e1adxYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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