SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7d57ad58daa871ab5a0fce9a182f7799d77111818f58eb93518584ff415d55f' 
  AND token = 'MkMGN6sB0pwR82TAvLdBPLCcPoYBBWHLlg/RGcyR6Y4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}