SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b68604e8ef2d87613a148fcc47f2023ec6a5ca84657429d39b9605abb4a9349' 
  AND token = 'PBXp2sedHm5fex9TOMJ00Fo3Es23gImoSJMKn5Pimcg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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