SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f89c2bc3bf716c9a00e4507feac82a83df480d5cc20f873237827f0ddc55dc8' 
  AND token = 'kguQA+WJebxp0iIceh3V9Y2Qx2cAKiQF5ErUCJ6fbFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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