SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '477d4cd5b0d48a756f8ef9ce8b3420407b429b6e35ab8445545f2aedc115435f' 
  AND token = '3VHbJAIYkOee0DdBBfv7WYVFbLROSPLJAQYCPA14TqU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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