SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8577584f0ab77985091e2699b6d77833dc673e65f4fe6b2db4a2f53483c80d7' 
  AND token = 'CJeylsNC+QzX3FSt9DZj7vBIqJm4Le4bvUM/2JvnxJ4=' 
  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"
    }
  }
}