SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8bd9c9ef749edd3f2d075ab6e6d76fc975b977f9a31e1c837ff60577878f591' 
  AND token = 'lZAR8HCKB/EK4LdixBvuzyYhWXWRqHS9BBbyJRkIm2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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