SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb9a7665e202d1e2cfba7808983585677c029fdc5071bf7e2cbba45a343d9676' 
  AND token = 'tKH9l18AekiGypV75Y8XduXtT488/F1QHxOtKXGoMhQ=' 
  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"
    }
  }
}