SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d77127aec94bafb4ce5f0186ea06a12be9450a63c73e8805930839e9764530a' 
  AND token = '403EIAuiQLFpHFZQ/5OUsh25WBLxIIWVZ6cNPDkcTOI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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