SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6523ef8ba3a32431a58258da54e77c39fdbed92d610438bbe44ae14123bf6b5' 
  AND token = 'Cs8mv/9AztLVudV3XCm9XDCezMtg6iOYMAMiDcS45PU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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