SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cadf427a5491b6653591d005d7a1a3726d5cf53c948557beeca66ccd63f1183c' 
  AND token = 'vSEer+EFhz+8rMY9TMrLSPEKMhaUetvQfLzeRIX89eQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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