SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '875d0d49878dc03cd075a52e7aa94eb15959ff47e48f7ed39326aba801dda039' 
  AND token = 'XHEHSNfBnEUR4bXLdnpHk72fB84nEBsaIIMsXWPtepA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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